Welcome to our 2021 Boston Red Sox in Review series. This is, as you can probably guess, where we will be reviewing all of the players who made at least a modest impact on the Red Sox in 2021. Every week day we’ll be deep diving into one player, describing the season in a sentence, looking at the positives from the year as well as negatives, looking back at our one big question from our season preview and looking ahead to the 2022 season. Today we finish things out with a look at Garrett Whitlock’s 2021 campaign.
2021 in one sentence
Garrett Whitlock went from being a Rule 5 Draft selection by a last-place team hoping to add depth to the best reliever on a club that went to the ALCS.
Of all the things that broke right for the Boston Red Sox in 2021, nothing was as unexpected as Garrett Whitlock’s ascension to the top of the team’s bullpen depth chart. Cast off by the New York Yankees in the Rule 5 Draft, Whitlock came to Boston with some definite promise but no immediate expectations. Then he started pitching.
In his first six regular season outings for the Red Sox, he didn’t give up a single run and struck out 18 batters in 13 1⁄3 innings. Following the same surprising trajectory of the team itself, what began as a nice start for Whitlock just kept going. While everyone waited for the other shoe to drop, he just kept slicing up opposing lineups, earning the right to pitch in more meaningful spots along the way. By the time the regular season came to a close, Whitlock had amassed more wins above replacement than any other full-time reliever on the Red Sox’s roster (1.6 fWAR and 3.0 bWAR). Because of how well he pitched, Whitlock wasn’t just the most valuable reliever on the roster; he was also the most utilized, throwing 73 1⁄3 innings in total.
Whitlock’s incredible campaign was buoyed by exceptional run prevention work. In addition to his stunning 1.96 ERA, Whitlock had the peripheral goods, as he posted a 2.84 FIP, with his expected numbers also in strong positions (2.96 xERA and 3.22 xFIP). In fact, based on ERA-, Whitlock was 57 percent better than league average, which is quite the feat for someone who had not pitched above Double-A before 2021.
In addition to his stunning ability to quiet offenses, Whitlock managed to produce above average strikeout and walk rates (27.2 percent and 5.7 percent, respectively) using a four-pitch repertoire with more than one plus offering. According to Baseball Savant, the hard-throwing right-hander produced solid run values with his sinker (-10), slider (-7) and four-seam fastball (-4). (Remember, negative run values are good in this case). His changeup was the underachiever of the group and still wound up with a run value below zero.
Whitlock’s sinker was his preferred offering, according to Baseball Savant, as he threw it 51 percent of the time, but with its speed (95.8 miles per hour on average) coming in roughly the same as his four-seamer (96.2 miles per hour), it worked effectively as a fastball. Regardless of what you call it, Whitlock was in the 86th percentile in fastball velocity in 2021, so there’s no arguing that he threw hard.
For this section, we’ll pick back up right where we left off. Whitlock could certainly put lightning in his pitches, but his fastball could be a little flat, ranking in the 20th percentile in spin rate, according to Baseball Savant. In addition, while his slider was effective, its break wasn’t overly impressive.
As you would expect, Whitlock was pretty good in clutch spots, but he will need to improve if the plan is to make him a closer. He had a 3.74 FIP in high leverage situations last season, which is far from resume-crushing, but could stand to drop a bit. That’s especially true if Whitlock hopes to have a better run in the postseason. This past fall, he may have had a 2.16 EREA in the playoffs, but his peripheral numbers (16.7 percent strikeout rate, 5.81 FIP) were not as kind. He can certainly be excused for some of that. After all, he injured his arm right at the end of the season and we are still talking about a guy who was in his first MLB season.
Where some of that explanation doesn’t yield fruit is in Whitlock’s surprising season-long struggles against lefties. It didn’t end up hurting him all that much, but he had a 4.46 FIP vs. southpaws and a 2.06 FIP against righties, so it’s worth mentioning.
The Big Question
The big question (pardon the pun) for Whitlock going forward is whether he will be used as a reliever or a starter. He certainly proved he can cut it in the bullpen, and to answer our question from earlier this year, it seems like he might have pitched too well in relief to be moved to the rotation. With the Red Sox signing Rich Hill, James Paxton and Michael Wacha and Tanner Houck looking like a good bet for another rotation spot, there isn’t necessarily a clear path for Whitlock. Plus, considering how Matt Barnes fell apart in the second half of 2021, the Red Sox could use some certainty in the late innings. That’s not to say Whitlock will never be a starter, but I think he might be pitching out of the bullpen for at least one more season.
2022 and Beyond
After the season he just had, there’s no way Whitlock doesn’t have a prominent role with the Red Sox in 2022. It’s still up for debate what his actual position will be, whether it be full-time closer, set-up man or swing guy, but he will be an important piece of the Red Sox’s pitching puzzle for years to come, especially since he won’t be an unrestricted free agent until after the 2026 season (under the current CBA rules, at least).
Now, remember that other shoe I mentioned earlier? For those still waiting, Whitlock’s body of work from 2021 has enough positives below the surface to make it seem like that shoe will be stuck up there forever. Whitlock didn’t just get lucky with not giving up runs: He ranked in the 96th percentile in expected ERA, barrel rate and expected weighted on-base average as well as the 92nd percentile in expected slugging. Of course, expectations aren’t final results, but we just watched Whitlock overperform meager expectations for an entire season. I wouldn’t bet against him overcoming any speculation about his long-term success.